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1. Description of Related Art
Japanese Patent Publication No. 7-320842 discloses a connecting method of two different covered wires as shown in FIGS. 1A and 1B. The shown method is related to a connection between a shield wire W1 and a ground wire W2. The shield wire W1 has a core line 14 as a conductive part covered with a resinous cover 8 and a shielding braided wire 13 as another conductive part which covers the resinous cover 8 and is also covered with another resinous cover 7. While, the ground wire W2 has a core line 15 as a conductive part covered with a resinous cover 9.
In order to connect the shield wire W1 with the ground wire W2, it is executed at the first step to put the connecting (overlapping) part defined by the wire W1 and the wire W2 between a pair of resinous tips 1, 3. In detail, the resinous tip 3 is inserted into an anvil 5 and subsequently, the shield wire W1 is inserted into the anvil 5 and put on the resinous tip 3. Further, the ground wire W2 is inserted and put on the inserted shield wire W1 and finally, the other resinous tip 1 is laid on the ground wire W2.
At the second step, it is carried out to partially remove the resinous covers 7, 9 of the wires W1, W2 by heating the connecting part defined by the wires W1, W2 under pressure and further seal the resulting connecting part by welding the resinous tips 1, 3 each other. In detail, a horn 11 is inserted from the upside of the resinous tip 1 and continuously, the tips 1, 3 are heated due to ultrasonic oscillations between the horn 11 and the anvil 5 under pressure. Owing to the generation of heat by the ultrasonic oscillations, the covers 7, 9 are molten at the connecting part, so that the braided wire 13 of the shield wire W1 and the core line 15 of the ground wire W2 are exposed together.
While, the so-molten covers 7, 9 are pushed out of the resinous tips 1, 3 through a clearance therebetween, so that the braided wire 13 comes into electrical contact with the core line 15. With further continuation to both oscillate and pressurize, the resinous tips 1, 3 are molten for their integration, so that the connecting part can be sealed as shown in FIG. 1B.
In the above-mentioned connecting method, however, there is a possibility that the shield wire""s portion close to the resinous tips 1, 3, i.e., a part 17, is influenced by the heat of the resinous covers 7, 9 pushed out of the resin tips 1, 3 (see FIG. 1B), thereby causing the deterioration of insulation effect, the disconnection of conductive wire, the deterioration of bending, etc.
FIG. 2 shows respective sections of the shield wire W1 and the ground wire W2 in their sealed connection which is somewhat different from the previously-mentioned connecting structure. Shown in the figure is a condition where a resin 19 resulting from the melting of the ground wire W2 is pushed out from the clearance between the resinous tips 1, 3, so that the ground wire W2 is damaged at its part 21 close to the tips 1, 3 by the heat of the so-pushed resin 19, causing the exposure of the core line 15.
Therefore, also in this case, there may be caused problems of the deterioration of insulation effect of the cover 9 at a part of the ground wire W2, the disconnection of the core line 15 and the deterioration of bending, too.
2. Field of the Invention
The present invention relates to a connecting method of connecting two different wires to each other, for example, an electrical connection between a shield wire and a ground wire, and also relates to a pair of recessed resin tips which are appropriate in the connecting method.
Under the circumstances, it is therefore an object of the present invention to provide a connecting method of connecting covered wires with each other, by which it is possible to prevent the molten insulating covers from being pushed out of the resin tips. Further, it is another object of the invention to provide resin tips which are appropriate in connecting the covered wires in accordance with the above method.
The former object of the present invention described above can be accomplished by a connecting method of connecting a first wire with a second wire, the first wire having a first conductive wire covered with a first insulating cover, the second wire having a second conductive wire covered with a second insulating cover, the connecting method comprising:
a first step of putting a connecting part constituted by both of the first and second wires, between a first resin tip and a second resin tip; and
a second step of heating the connecting part through the first and second resin tips under pressure thereby to remove the first and second insulating covers from the connecting part while welding the first and second resin tips together thereby to sealing the connecting part. In the method, at least either one of the first and second resin tips is provided, on both sides of the connecting part, with first recessed parts. While, at least either one of the first and second resin tips is provided, on both sides of the connecting part, with second recessed parts. Thus, the molten first insulating cover of the first wire is accommodated in the first recessed parts at the second step, while the molten second insulating cover of the second wire is accommodated in the second recessed parts at the second step.
In this way, it is possible to restrict the first and second covers of the first and second wires from being pushed out of the integrated resin tips, thereby avoiding the damage on the first and second wires due to heat of the so-pushed covers.
In this way, the exposure of the first and second conductive wires outside the first and second resin tips is restricted, so that the bending capabilities of the first and second wires can be maintained without causing the deterioration of insulation effect and the disconnection of the first and second conductive wires, etc.
Additionally, since the molten and removed first and second insulating covers are accommodated in the first recessed parts and the second recessed parts smoothly, it is possible to accomplish the shortage of welding time and the reduction in the number of working processes.
According to the present invention, the latter object of the invention can be accomplished by a combination of first and second resin tips which are usable in a connecting method of connecting a first wire with a second wire, the first wire having a first conductive wire covered with a first insulating cover, the second wire having a second conductive wire covered with a second insulating cover, the connecting method comprising a first step of putting a connecting part constituted by both of the first and second wires, between a first resin tip and a second resin tip and a second step of heating the connecting part through the first and second resin tips under pressure thereby to remove the first and second insulating covers from the connecting part while welding the first and second resin tips together thereby to sealing the connecting part. In this invention, the combination comprises first recessed parts formed at least either one of the first and second resin tips and arranged on both sides of the connecting part, for accommodating the molten first insulating cover of the first wire therein and second recessed parts formed at least either one of the first and second resin tips and arranged on both sides of the connecting part, for accommodating the molten second insulating cover of the second wire.
In the above-mentioned combination, preferably, the first recessed parts and the second recessed parts are continuously formed in one of the first and second resin tips so as to surround the connecting part in annular.
In this case, the molten first insulating cover can flow from the first recessed parts into the second recessed parts or conversely, the molten second insulating cover part can flow from the second recessed parts into the first recessed parts, accomplishing the smooth accommodation of the molten covers.
In the above-mentioned combination, more preferably, the second recessed parts are formed in the other of the first and second resin tips.
In this case, it is possible to accommodate the molten second insulating cover of the second wire more smoothly.
According to the invention, there is also provided a combination of first and second resin tips which are usable in a connecting method of connecting a first wire with a second wire, the first wire having a first conductive wire covered with a first insulating cover, the second wire having a second conductive wire covered with a second insulating cover, the connecting method comprising a first step of putting a connecting part constituted by both of the first and second wires, between a first resin tip and a second resin tip; and a second step of heating the connecting part through the first and second resin tips under pressure thereby to remove the first and second insulating covers from the connecting part while welding the first and second resin tips together thereby to sealing the connecting part.
The above invention is characterized in that the first and second resin tips have respective drawing parts formed to accommodate the first wire to be drawn out of the first and second resin tips, the drawing parts have diameters gradually increased toward the outside ends of the drawing parts.
Then, even if the first wire shakes, the above-mentioned configurations of the first and second resin tips allow the first wire to come into surface contact with the drawing parts in their weakened xe2x80x9cedgexe2x80x9d effect. Therefore, it is possible to improve the tips"" force to retain the first wire at the connecting part and also the bending capability of the first wire in relation to the first and second resin tips.
According to the invention, there is also provided a pair of resin tips used for connecting conductive parts of two different covered wires with each other while removing insulating covers of the wires. In the invention, the pair comprises a first resin tip having a welding part formed at an intermediate portion thereof, first recessed parts formed on both sides of the welding part and second recessed parts also formed on both sides of the welding part, the first and second recessed parts being continuously arranged around the welding part and a second resin tip having recessed parts formed corresponding to the second recessed parts of the first resin tip.
Also in this invention, the operation and effects brought by the pair of resin tips are similar to those brought by the above-mentioned combination of the first and second resin tips.
Also in this invention, preferably, the welding part of the first resin tip has a semicircular-shaped recessed part formed for accommodating one of the wires and semicircular-shaped stepped parts arranged on both sides of the recessed part and also formed deeper than the semicircular-shaped recessed part.
Then, it is possible to restrict the first and second covers of the first and second wires from being pushed out of the integrated resin tips, thereby avoiding the damage on the first and second wires due to heat of the so-pushed covers.
Also in this invention, more preferably, the first and second resin tips have respective drawing parts formed to accommodate one of the wires to be drawn out of the first and second resin tips, the drawing parts have diameters gradually increased toward the outside ends of the drawing parts.
Similarly, it is possible to improve the tips"" force to retain the first wire at the connecting part and also the bending capability of the first wire in relation to the first and second resin tips.
These and other objects and features of the present invention will become more fully apparent from the following description and appended claims taken in conjunction with the accompany drawings.